import { app, BrowserWindow, webContents } from 'electron';
import { monitorEventLoopDelay } from 'node:perf_hooks';

export type PerformanceSnapshot = {
  capturedAt: number;
  eventLoopDelayMs: number;
  gpu: ReturnType<typeof app.getGPUFeatureStatus>;
  processes: Array<{
    pid: number;
    type: string;
    cpuPercent: number;
    workingSetSize: number;
  }>;
  windows: number;
  webContents: number;
  background: {
    activity: { visible: boolean; module: string | null };
    leaseCount: number;
  };
};

type LifecycleDiagnostics = {
  getActivity(): { visible: boolean; module: string | null };
  getLeaseCount(): number;
};

// Keep the sampler alive for the process lifetime, but only expose aggregate
// histogram values. No request payloads, URLs or project data enter this
// diagnostic path.
const eventLoopMonitor = monitorEventLoopDelay({ resolution: 20 });
eventLoopMonitor.enable();

export function collectPerformanceSnapshot(lifecycle?: LifecycleDiagnostics): PerformanceSnapshot {
  const eventLoopDelayMs = eventLoopMonitor.max / 1e6;
  eventLoopMonitor.reset();
  return {
    capturedAt: Date.now(),
    eventLoopDelayMs: Math.round(eventLoopDelayMs * 100) / 100,
    gpu: app.getGPUFeatureStatus(),
    processes: app.getAppMetrics().map((metric) => ({
      pid: metric.pid,
      type: metric.type,
      cpuPercent: metric.cpu.percentCPUUsage,
      workingSetSize: metric.memory.workingSetSize,
    })),
    windows: BrowserWindow.getAllWindows().length,
    webContents: webContents.getAllWebContents().length,
    background: {
      activity: lifecycle?.getActivity() ?? { visible: true, module: null },
      leaseCount: lifecycle?.getLeaseCount() ?? 0,
    },
  };
}